The surnames Lawry and Lowry are both diminutives of the first name Lawrence. Adding -y to the first syllable of a male name was a popular device when forming surnames in medieval and early modern Cornwall, for example Eddy, Davy, Harry and, of course, Lawry.
While Lowry was the preferred spelling in the north of England, in Cornwall and south-west England it was Lawry. In the 1500s most spellings were Lawry, although examples of Lowry were not that uncommon even this early. Lorye first appeared in the parish registers as a local variant somewhat later at Bodmin in 1564.
Over the centuries the proportion of Lawrys gradually declined, from over 90% before 1600 to 67% in 1861. Consequently, the spellings Lowry and Lory became more frequent, in 1861 amounting to 19% and 14% of the total group respectively.